to construct an empty matrix with shape (M, N)
dtype is optional, defaulting to dtype=’d’.

csr_matrix((data, ij), [shape=(M, N)])

where data and ij satisfy the relationship
a[ij[0,k],ij[1,k]]=data[k]

csr_matrix((data, indices, indptr), [shape=(M, N)])

is the standard CSR representation where the column indices for
row i are stored in indices[indptr[i]:indptr[i+1]] and their
corresponding values are stored in data[indptr[i]:indptr[i+1]].
If the shape parameter is not supplied, the matrix dimensions
are inferred from the index arrays.

Notes

Sparse matrices can be used in arithmetic operations: they support
addition, subtraction, multiplication, division, and matrix power.